Chemical imaging is known in the art. One example of an apparatus used for chemical imaging is taught in U.S. Pat. No. 6,002,476, entitled “Chemical Imaging System,” to Treado et al. Another example of an apparatus used for chemical imaging is taught in U.S. Pat. No. 7,019,296, entitled “Near Infrared Chemical Imaging Microscope,” to Treado et al.
In conventional Raman imaging, a full-frame CCD (Charge Coupled Device) is used. However, with the use of a full-frame CCD, luminescence energy (from the same material and location of the sample) is also captured by the CCD collecting Raman photons, especially when luminescence occurs at the same energy level as the Raman photons. The optical “contaminating” effect of luminescence emissions may be reduced by photobleaching the sample material prior to Raman imaging. However, such additional step of photobleaching may not be always desirable or practicable depending on the sample material at hand. Therefore, it is desirable to devise a Raman imaging system that significantly avoids imaging the interfering luminescence and also avoids requiring sample photobleaching prior to Raman imaging.